The early events of transformation are being studied in the C3H/10T1/2 cell line using cancer chemotherapeutic agents. In addition, various inhibitors of transformation, particularly ascorbic acid, are being studied as well as their mechanism(s) of action. The production of sister chromatid exchanges by various cancer chemotherapeutic agents is also being investigated. Finally, we are studying the ability of various agents to block the induction of sister chromatid exchanges.